/*
 * Copyright (c) 2005, 2017, Oracle and/or its affiliates. All rights reserved.
 */
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: ExsltSets.java,v 1.1.2.1 2005/08/01 02:08:50 jeffsuttor Exp $
 */
package com.sun.org.apache.xalan.internal.lib;

import com.sun.org.apache.xml.internal.utils.DOM2Helper;
import com.sun.org.apache.xpath.internal.NodeSet;

import java.util.HashMap;
import java.util.Map;

import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 * This class contains EXSLT set extension functions.
 * It is accessed by specifying a namespace URI as follows:
 * <pre>
 *    xmlns:set="http://exslt.org/sets"
 * </pre>
 * <p>
 * The documentation for each function has been copied from the relevant
 * EXSLT Implementer page.
 *
 * @xsl.usage general
 * @see <a href="http://www.exslt.org/">EXSLT</a>
 */
public class ExsltSets extends ExsltBase {
    /**
     * The set:leading function returns the nodes in the node set passed as the first argument that
     * precede, in document order, the first node in the node set passed as the second argument. If
     * the first node in the second node set is not contained in the first node set, then an empty
     * node set is returned. If the second node set is empty, then the first node set is returned.
     *
     * @param nl1 NodeList for first node-set.
     * @param nl2 NodeList for second node-set.
     * @return a NodeList containing the nodes in nl1 that precede in document order the first
     * node in nl2; an empty node-set if the first node in nl2 is not in nl1; all of nl1 if nl2
     * is empty.
     * @see <a href="http://www.exslt.org/">EXSLT</a>
     */
    public static NodeList leading(NodeList nl1, NodeList nl2) {
        if (nl2.getLength() == 0)
            return nl1;

        NodeSet ns1 = new NodeSet(nl1);
        NodeSet leadNodes = new NodeSet();
        Node endNode = nl2.item(0);
        if (!ns1.contains(endNode))
            return leadNodes; // empty NodeSet

        for (int i = 0; i < nl1.getLength(); i++) {
            Node testNode = nl1.item(i);
            if (DOM2Helper.isNodeAfter(testNode, endNode)
                    && !DOM2Helper.isNodeTheSame(testNode, endNode))
                leadNodes.addElement(testNode);
        }
        return leadNodes;
    }

    /**
     * The set:trailing function returns the nodes in the node set passed as the first argument that
     * follow, in document order, the first node in the node set passed as the second argument. If
     * the first node in the second node set is not contained in the first node set, then an empty
     * node set is returned. If the second node set is empty, then the first node set is returned.
     *
     * @param nl1 NodeList for first node-set.
     * @param nl2 NodeList for second node-set.
     * @return a NodeList containing the nodes in nl1 that follow in document order the first
     * node in nl2; an empty node-set if the first node in nl2 is not in nl1; all of nl1 if nl2
     * is empty.
     * @see <a href="http://www.exslt.org/">EXSLT</a>
     */
    public static NodeList trailing(NodeList nl1, NodeList nl2) {
        if (nl2.getLength() == 0)
            return nl1;

        NodeSet ns1 = new NodeSet(nl1);
        NodeSet trailNodes = new NodeSet();
        Node startNode = nl2.item(0);
        if (!ns1.contains(startNode))
            return trailNodes; // empty NodeSet

        for (int i = 0; i < nl1.getLength(); i++) {
            Node testNode = nl1.item(i);
            if (DOM2Helper.isNodeAfter(startNode, testNode)
                    && !DOM2Helper.isNodeTheSame(startNode, testNode))
                trailNodes.addElement(testNode);
        }
        return trailNodes;
    }

    /**
     * The set:intersection function returns a node set comprising the nodes that are within
     * both the node sets passed as arguments to it.
     *
     * @param nl1 NodeList for first node-set.
     * @param nl2 NodeList for second node-set.
     * @return a NodeList containing the nodes in nl1 that are also
     * in nl2.
     * @see <a href="http://www.exslt.org/">EXSLT</a>
     */
    public static NodeList intersection(NodeList nl1, NodeList nl2) {
        NodeSet ns1 = new NodeSet(nl1);
        NodeSet ns2 = new NodeSet(nl2);
        NodeSet inter = new NodeSet();

        inter.setShouldCacheNodes(true);

        for (int i = 0; i < ns1.getLength(); i++) {
            Node n = ns1.elementAt(i);

            if (ns2.contains(n))
                inter.addElement(n);
        }

        return inter;
    }

    /**
     * The set:difference function returns the difference between two node sets - those nodes that
     * are in the node set passed as the first argument that are not in the node set passed as the
     * second argument.
     *
     * @param nl1 NodeList for first node-set.
     * @param nl2 NodeList for second node-set.
     * @return a NodeList containing the nodes in nl1 that are not in nl2.
     * @see <a href="http://www.exslt.org/">EXSLT</a>
     */
    public static NodeList difference(NodeList nl1, NodeList nl2) {
        NodeSet ns1 = new NodeSet(nl1);
        NodeSet ns2 = new NodeSet(nl2);

        NodeSet diff = new NodeSet();

        diff.setShouldCacheNodes(true);

        for (int i = 0; i < ns1.getLength(); i++) {
            Node n = ns1.elementAt(i);

            if (!ns2.contains(n))
                diff.addElement(n);
        }

        return diff;
    }

    /**
     * The set:distinct function returns a subset of the nodes contained in the node-set NS passed
     * as the first argument. Specifically, it selects a node N if there is no node in NS that has
     * the same string value as N, and that precedes N in document order.
     *
     * @param nl NodeList for the node-set.
     * @return a NodeList with nodes from nl containing distinct string values.
     * In other words, if more than one node in nl contains the same string value,
     * only include the first such node found.
     * @see <a href="http://www.exslt.org/">EXSLT</a>
     */
    public static NodeList distinct(NodeList nl) {
        NodeSet dist = new NodeSet();
        dist.setShouldCacheNodes(true);

        Map<String, Node> stringTable = new HashMap<>();

        for (int i = 0; i < nl.getLength(); i++) {
            Node currNode = nl.item(i);
            String key = toString(currNode);

            if (key == null)
                dist.addElement(currNode);
            else if (!stringTable.containsKey(key)) {
                stringTable.put(key, currNode);
                dist.addElement(currNode);
            }
        }

        return dist;
    }

    /**
     * The set:has-same-node function returns true if the node set passed as the first argument shares
     * any nodes with the node set passed as the second argument. If there are no nodes that are in both
     * node sets, then it returns false.
     * <p>
     * The Xalan extensions MethodResolver converts 'has-same-node' to 'hasSameNode'.
     * <p>
     * Note: Not to be confused with hasSameNodes in the Xalan namespace, which returns true if
     * the two node sets contain the exactly the same nodes (perhaps in a different order),
     * otherwise false.
     *
     * @see <a href="http://www.exslt.org/">EXSLT</a>
     */
    public static boolean hasSameNode(NodeList nl1, NodeList nl2) {

        NodeSet ns1 = new NodeSet(nl1);
        NodeSet ns2 = new NodeSet(nl2);

        for (int i = 0; i < ns1.getLength(); i++) {
            if (ns2.contains(ns1.elementAt(i)))
                return true;
        }
        return false;
    }

}
